Drier



March 26, 1929.

D. S. BAKER Filed June 29, 1926 I DRIER 2 Sheets-Sheet 2 Patented Mar. 26, 1929.

UNITED s'lizvrnsA DAVID S. BAKER, F GREENWICH, CONNECTICT.

DRIER.

Application led June 29, y

This application relates to driers for evaporating moisture from various materlals, such as paints, paint materials, chemicals and other substances, and particularly tothe type of driers in which a stream of dryingmedium is retained. at the proper temperature and the moisture content by passing it over reheaters between its successive contacts with masses of the material to be dried.

An object of the invention is to provide a new means for controlling the reheating of the drying medium which permits'a simplification of the construction of such driers. A further object isto provide for the use of flue pipes containing products of combustion both for preheating andreheating the drying medium.- l

The invention is of a special value when ap plied to the .so-called Gordonntype of drier, shown for example in U. S. Patents \Nos. 1,405,780 and 1,504,854, in which the drying medium is passed at high linear velocity through a tortuous passage formed by stag gered overlapping flow directing members in a drying chamber. In such driers, the temperature of the drying mediumithroughout its course through the tortuous passage has been controlled by regulating the supply of heating medium to, and thus the heat of, each reheater. 4This arrangement necessitates thel expense of a separately controlled heater a"t each point at which the drying medium is to be reheated, and of course, precludes the use of liuc pipes as a reheating means.

Tn accordance with the present invention, the reheating of the drying medium is controlled by regulating ther proportionof the stream of drying medium which comes in contact with each reheater, so' that the heat absorbed by the drying medium from each re-V heater may accurately be controlled without varying the amount of heating medium supplied to the reheaters. This makes possible the use of a single heating element to reheat the drying medium at several different points in its course, and thus facilitates the use of flue pipes for reheaters. f v. v

This and other featurcsmay best lbe understood `trom a detailed description of a specific drier 'of the Gordon type embodying the 192e. serial no. 119,301.

invention which is shown lin the accompanying drawings, in which Flg. 1 is a front elevation of the drier sectioned on the line vlf-.l of Fig. 2 and Fig. 3;

Fig 2 1s a plan view of the top of the 55 drler; and Fig. 3 is a horizontal line 3;-3 of Fig. 1. The drier illustrated has a rectangular casing 10 most desirably constructedof insulat- 60 ing material. .In the casing is an open racl 11 supporting oppositely facingangle irons 12 for holding a series of .-'uperimposedhorizontal trays 13 for supporting masses'of the. materialto be dried. The front ofthe casing contains a door 14 through which the trays 13 may be removed. f l f Air. or other drying medium is forced into V the chamber by a blower 15,`whose 'discharge 1s connected by an expanding conduit 16 with 70 an inlet openingl at Hthe top ofthe casing near one of its side walls. After circulating' wlthm the casing in the manner hereinafter described, the air may bedischarged through i section taken on the la valve controlled outlet opening 18 in the '75' caslng, or all or a part of it may be recircu-v f lated by drawing it back into the blower through avalve controlled opening 19 in the. top ofthe casing.u

Are box '20 is'located in one side'oiz' the-F80 casing near its bottom. The fire box may contain a gas burner 21, and mayf be supplied with air through an opening 22 in the bottom of the casing. From tlie'top 23- of theiire box, twol sets of flues 24,25 extend vertically '35 upward through the casing at one side of the rack 1-1. Theseues extend out through the top of they casing and pass through the conduit 16. Their upper ends may be connected by'a hood 26 with a chimney 27. It will be no understood that as the' products 'of combustion from Jthe fire box 20 pass through the. iues 24, 25,- the lower portions of the flues are hotter than the upper portions thereof. The heat and the flots7 of the flue gas .may be 95 retained constant throughout the operation of the'drier. v

The lowest tray 13 is on a level with the top 23 of the` frebox, and'co-operates @ith the' top of the-{irebox anda. partition 28 in 100' I of which it is reheated. The descending and ascending parts of the How passage are separated by -a partition 33 having an upper vertical portion 34 located between the outer Hue pipes 24 and a side wall 35 of the casing, a lower vertical portion 36 located between the two sets4 bf Hue pipes, and a short horizontal connecting portion 37. Y

Inl the part of the chamber between the partition 33 and the side wall 39 of the casing are a set of horizontal Howdirecting members 40, 50,60, 70. These members are staggered, the members 40 and 60 extending from the partition 33, and the members 50 and extending from the side wall 39. In the particular form illustrated, each How directing member is formed in part by one of the trays 13. The lowest of these members, 40, consists of a horizontal partition .41, extending from the lower end of the partition 33, and the tray 134. The next, How directing member, 50, consists of a horizontal partition 51, extending from the wall 39 the tray 135, and a partition 52, extending rom the end of this tray through the inner set of Hue pipes 25. The next, 60, is formed by a horizontal partition 61, extending ,from the partition 33 on the level with its horizontal portion 37, and theV tray 13". The last How directing member, 70, is formed by a horizontal partition 71, extending from the wall 39, the tray 13", and a partition 72 extending from. the edge of this tray to and through the outer set o Hue pipes 24.

vIt is apparent that the tortuous ascending passage formed by the How directing members just described hasia bend 80, through which extend the lower portions 81 of the Vinner Hue pipes 25, and another bend 90, through which extend the upper portions 91, 92 of both sets of Hue pipes. These portions of Hue pipes consequently serve as reheaters in the bends of the tortuous passage. It should be n oted that the reheating thus provided by. the Hue pipes is approximately uniform,smce the reheater 81 in the bend 80 is hotter than the reheater 91, 92 in the bend 90 but has a smaller radiating surface. A l

All parts of the Hue pipes, except the portions 81, 91, 92 in the bends of the tortuous passage, are used for the initial heatin or preheating of the drying medium. ome prheating is caused in the conduit 16 by the extreme upper portions 82, 83 of the Hue pipes. The principal preheating occurs in the lower half of the descending passage V31, where the drying medium is brought into contact with the lower portion 84 of the outer Hue pipes 24j-.ry staggered baffles 85, 86. Additional preheating is caused by the extreme lower portion 87 of the inner Hue pipes 25 and by the top 23 of the fire box.

norder to provide or separate and accurate control of the reheating in the bends and 90 of the tortuous passage 32, bypass openings 53, 73, 73 are provided4 in the partitions 52 and 72. The by-pass opening 53may extend the wholeV length of the drier between the inner Hue pipes 25 and the tray 135. It is controlled by a movable valve member or vane 54. The by-pass openings 73, 73' are located respectively between the inner Hue pipes 25 and the tray 137, and between thetwo sets of Hue pipes, and are controlled by valve members or movable vanes 74, 7 4. The movable vanes 54, 74, 7 4 are fixed on hinge rods 45,65,65pivotally mounted at the inner edges of the outer fixed portions, 76, 76 of the partitions 52 and 72. The vanes are provided with separate handles 5,7, 77, 77 projecting through the front wall of the drier, so that the position of each vane may be controlled' independently of the other vanes.

The regulation of the reheating of the drying medium, by means of the vanes 54, 74, 7 4, depends upon the fact that the amount of heat absorbed by the drying medium from each reheater is a function of the difference between the temperature of the drying medium in contact with the reheater and the temperature of the reheater itself, or more accurately of the Hue gases within the reheater: The greater the temperature difference between the drying medium in contact with the reheater and the Hue gases within it, the more rapidly is heat absorbed by the drying medium from the Hue gases. Consequently, whenl the vane 54 vis placed in closed or horizontal position, so that the entire stream of drying medium is brought into iiitimate contact with the reheater 81 formed by the lower portion of the inner Hue pipes 25,.a maximum amount of heat is absorbed by the stream from the Hue gases within the reheater. When this vane is turned to a vcrtical position completely uncovering the bypass opening 53, only a small part of the stream comes in contact with the reheater 81.

As the volume ofv the part of the stream coming in ContactJ with the lreheater is small, this part of the stream rises in temperature rapidly, and therefore absorbscomparatively little heat from the Hue gases within the reheater. The other part of the stream which passes through the by-pass opening 53, and therefore is not reheated at all, mixes with the part of the stream which has passed in contact with the reheater, thus making the average temperature of the stream above the How directing member 50 less than was the case when the entire stream was brought into `may be controlled in Ia similar manner by means of the vanes 74 and 74', except in this case the control'is even more accurate since the stream may be divided into three parts,

one of which passes through the opening 73" which is not reheated, While the second passes over the flue pipes 25, and the third passes over these flue pipes and the outer flue pipes 24.Y

In the drier which has been described, the' outer lxed'portions 56 and 76 of the par-y titions 52, 72, are not' essential, andfmay be omitted without materially detracting from efficiency of the drier. Furthermore, itfis not` essential that the staggered overlapping partit-ions and the bottom of the chamber be formed in part by ther trays containing vthe material to be dried; and the reheating of the drying medium need not be limited to the bends of the tortuous passage at only on-e side of the trays. a verysimple and efficient embodiment of the various features of my invention, but I wish it' clearly understood that the invention is by no means limited to this 'specific embodiment.

What is claimed is: l

l. In a drier, means providing a flow pas slage, means for causing a drying medium to flow through the passage, supports for the material to be dried arranged in series in the passage, a plurality of reheaters in the passage, each located between two\of said supports, individually adjustable means for regulating the proportion of the stream of drying medium brought into Contact With each reheater, to control thereheating of the V dryingtmedium without varying the supply of heating medium to the reheaters.

2. In a drier, means providing a flow passage, means for causing a drying medium to ilow through the passage, supports for the material to be dried arranged in series .in the passage, a continuous h-c-atingelement extending through the flow passage at a plurality of diferent points between said supports, separately adjustable means for regulatingthe proportion of the stream of drying I nedlum brought into contact withl the heat1ng-element at each such point, to control the` reheating of the drying medium without varying .the supply of heating medium to the heating element. .c

3. In a drier, a continuous wall enclosing a plurality of chambers open only at their ends and pairs of passages connecting the The drier described is outlet end of each chamber with the inlet of the next chamber, means for supporting material to be dried Within each of said chambers, means for causing a drying medium to flow through said chambers, a reheater in one passage of each of`said pairs of passages, a valve in the other passage of said each pairs of passages, and means for separately adjusting each of said valves.

4. In a drier, a continuous wall enclosing a flow passage and a by-pass between two spaced points of said passage, means for causing a drying medium to flow through the passage, airst support for material to be dried located inf, the passage ahead of said by-pass, a second'support for material to be dried located in the passage behind said by-pass, a reheater located in the passage between the said two points connected by said bypass, and a valve located and'movablc within the /enclosed passage to control the by-pass.

5. In a drier, means providing a tortuous flow passage having closely spaced parallel straight portions connected by bends, means for supporting the material to be dried in the straight portions of the flow passage, means for causing a drying medium to low through the passage, reheaters located in bends of the passage, and separately adjustable means for by-passing a part of the stream of drying medium from the straight portion of the passage in front of each such bend to the next straight portion of the passage.

6. In a drier, means providing a tortuous flow passage consisting of closely-spaced parallel straight portions connected by bends,

iou

means for causing a drying medium to :flow Y throughxthe passage, means forsupporting the material to be dried in the straight portions vof the passage, a single heating element extending through a'plurality of bends of the passage, and separately adjustable means for y-passlng a part of the stream of drying medium from the straight portion in front of each of said bends to the straight portion beyond it. n Y

'7. A drier having an enclosed chamber, a plurality of staggered overlapping flow di# recting members forming a continuous tortuous enclosed passage vin said chamber, means for supporting the material to be dried between the overlapping portions of said flow directing members, a` reheater located between a side wall of the chamber and the by-pass opening.

`8. A drier having a chamber, a plurality of staggered overlapping low directing members forming a contlnuous tortuous passage in the chamber, means: for supporting n the material' to be dried between the overlapping portions of said flow directin members, areheater located between a wal of thel chamber and the endo'f one of said flow dil .rectingi members, a secondreheater located between said first reheater and the material to be driednsaid flow directing member containingv by-passop'enings located on oppofsite sides of said second reheater, and independently adjustable valves controlling said by-pass openings.

9. A drier havingl a chamber, staggered overlapping iiow directing members forming a continuous tortuous low passage in said chamber, a straight heating element at i one side of the chamber passing through the low directing members which extend to that side ofthe chamber and spaced from the ends of the'other l'ow directing members, movable vanes located between the ends of said other flow directing members andXsaid heating element, and an .independent means for regubetween said heating pipe and"u Ithe ends of the partitions which extend from the opposite Wall of the chamber. A

11. A drierhav'ing means providing passage, a plurality of supports for the ma erial to be dried arranged in series in said passage,

means for causing a drying medium .to flow through said passage, attire box, and -a plurality of Hue pipes extending from said lire box, portions of s'ome of said pipes near the fire box passing across the ilow passage to reheat the'drying medium between two of its contacts with the material to be. dried,

' and portions of a greater number o'f said pipes further from the irebox pas'sing across said passage at another point to cause a similar reheating of the drying medium between two other ofits contacts with the material `to be4 dried.

12. A drier having means providing 'a passage, a plurality of supports for the material to be dried arranged in series in said passage,

-means forcausing a drying medium to flow through said passage, a fire box, a plurality "of flue pipes extending from said fire box, 'portions of some of said pipes near the fire box passing across the flow passage to reheat the drying medium between two of its con- .,tacts with the material to be dried, andportions of a greater number of said pipes further from thel lire box passing across lsaid assage at' another point to cause a simiar` reheating of the drying medium between'two other of its contacts with the maportions of said pipes which are not withinthe low passage'to heat the drying medium before itenters the flow passage.

`13. A drier having a chamber, a fire box below said chamber, a plurality of vertical pipes conducting the products of combustion from said heater through the chamber, flow directing members in the chamber providing a tortuous passage having straight portions containing the material `to be dried and a bend which encloses a lower portion of some of said heating pipes aridiJ another bend which encloses an upper portion of a greater number of said heating pipes, and means for causing a drying medium to flow through said passage.

14. A drier having a chamber, a lire box belowsaid chamber, a plurality of vertical pipes conducting the products of coinbustion from said heater through the chamber, flow directing members in the chamber providing a.tortuous passage having straight portions containing the material to be dried and abend which encloses a "lower portion of some of said heating pipes and another bend which encloses an upper portion of a greater number of said heating pipes, and means for causing a drying medium'to flow over the portions of said pipes not within saidc liow passage and then through the flow passage.

15. A drier having a chamber, staggered overlapping horizontal flow directing members forming a continuous tortuous flow passage in the chamber, means for su porting .the material to be dried between tie overlapping portions of said flow directing members, a gas heater below the chamber, vertical flue pipes extending from said gas heater to the top of the chamber through the.

bends of said tortuous flow passage to relicat the drying medium between its contacts with the material to be dried.

16. A drier comprising a chamber having inlet and outlet openings at its top, a gas heater ocated below the chamber, two sets of vertical flue pipes extending from the heater through the chamber near one of its side walls, supports for the Amaterial to be .dried located in the central part of the'chamarate masses, causing a stream of heated drying medium to flow across one of the masses, ,then dividing said stream into separate parts, reheating one part of Said stream, re-

uniting the parts of said stream, and cans to which the Istream is reheated between its ing the stream to ow over the next I nass of successive contaets with the successive masses 10 the material. which consists 'in by-passing a regulated po-` 18. In the method of drying which comportion of the stream Iaround each of the re- 5 prises causing a heatedstreamof drying meheaters.

dium to flow across alternately arrang =d re- In testimony whereof I have hereunto set heaters and masses of the material to be my hand.- I dried,'the method of Vregulating the` `degree s DAVID S. BAKER. 

